Gas Processing Apparatus Using Catalyst

This application claims priority to Korean Patent Application No. 2024-0055565 filed on Apr. 25, 2024 in the Korean Intellectual Property Office (KIPO), the entire contents of which are hereby incorporated by reference.

Example embodiments of the present inventive concept relates to a catalyst apparatus for processing an exhaust gas, and more preferably, to an exhaust gas processing apparatus capable of effectively raising the temperature of an exhaust gas and improving the reaction efficiency with a catalyst and the exhaust gas removal rate.

Perfluorinated compounds (PFCs) have a form in which some or all of hydrogen atoms in hydrocarbons are replaced with fluorine, and have many different types. Perfluorinated compounds are used in semiconductor and display manufacturing processes because they are mainly used as surfactants, resistant to heat, and have chemical resistance and anti-pollution properties.

However, perfluorinated compounds are difficult to decompose and have a very high global warming potential, so they are regulated substances for environmental protection. Perfluorinated compounds generated in semiconductor processes and the like cannot be discharged to the outside and must be decomposed within the process and discharged as harmless gases and the like.

Direct combustion, plasma decomposition, catalytic decomposition methods, and the like have been used as methods for removing perfluorinated compounds. The mainly used catalytic decomposition method shows high decomposition efficiency and has the advantage of lowering device corrosion compared to other methods. However, there is a problem in that nitrogen oxides such as nitrous oxide (NO) generated during the decomposition process must be treated separately. Nitrous oxide is also included in the effluent generated during the semiconductor manufacturing process, and is known to be a powerful global warming agent having a global warming potential that is over 300 times that of carbon dioxide. Therefore, there is a need to develop technology capable of simultaneously treating perfluorinated compounds and nitrous oxide.

Accordingly, example embodiments of the present inventive concept are provided to substantially obviate one or more problems due to the limitations and disadvantages of the related art.

Example embodiments of the present inventive concept provide a catalyst apparatus capable of effectively raising the temperature of a target exhaust gas to be treated and effectively removing perfluorinated compounds and nitrous oxide at the same time.

In some example embodiments, a catalyst apparatus includes a heat exchange unit configured to raise the temperature of a first exhaust gas, which includes perfluorinated compounds or nitrous oxide, to form a second exhaust gas; a heating part into which the second exhaust gas is introduced and which is configured to form a third exhaust gas whose temperature is raised through a fluid flow that is repeated in a vertical direction from the bottom thereof; and a catalyst unit integrally formed with the heating part and configured to remove the perfluorinated compounds or the nitrous oxide in the third exhaust gas through the fluid flow repeated in the vertical direction from the bottom to form a first processing gas, wherein the first processing gas is introduced into the heat exchange unit and discharged as a second processing gas through a heat exchange action with the first exhaust gas, and the temperature of the second exhaust gas is higher than that of the second processing gas.

In other example embodiments, a catalyst apparatus includes a heat exchange unit configured to raise the temperature of a first exhaust gas, which includes perfluorinated compounds or nitrous oxide, through heat transfer plates to form a second exhaust gas; a heating part into which the second exhaust gas is introduced and configured to heat the second exhaust gas while moving the second exhaust gas in a zigzag pattern in a direction perpendicular to the ground to form a third exhaust gas; a catalyst unit integrally formed with the heating part and configured to remove the perfluorinated compounds or the nitrous oxide in the third exhaust gas to form a first processing gas; an inner housing in which the heating part and the catalyst unit are installed; and an outer housing installed outside the inner housing, wherein an insulating material is filled between the outer housing and the inner housing, and an exhaust gas supply part of the heating part is installed between the inner housing and the inner housing to supply the second exhaust gas to the heating part.

While the present inventive concept is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will be described in detail hereinafter. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the present inventive concept covers all modifications, equivalents, and alternatives falling within the spirit and scope of the present inventive concept. Like numbers refer to like elements throughout this specification.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Hereinafter, example embodiments of the present inventive concept will be described in further detail with reference to the accompanying drawings.

is a top plan view showing a catalyst apparatus for simultaneously removing perfluorinated compounds or nitrous oxide according to a preferred example embodiment of the present inventive concept.

Referring to, the catalyst apparatus has a heat exchange unit, a heating part, and a catalyst unit.

The heat exchange unithas a form in which a plurality of heat transfer platesare disposed within a heat exchange housing. A first processing gas is introduced through a processing gas inlet, and a second processing gas whose temperature is reduced while passing through the heat transfer platesis discharged through a processing gas outlet. Also, a room-temperature first exhaust gas is introduced into a space between the heat transfer platesthrough an exhaust gas inletand heated to the temperature of a second exhaust gas. Thereafter, the first exhaust gas is discharged through an exhaust gas outlet.

The first processing gas has a temperature range of 650° C. to 740° C. The temperature of the first exhaust gas is raised in two stages through a heat exchange action to form a second exhaust gas, and the second exhaust gas is introduced into the heating part. The heated second exhaust gas has a temperature range of 470° C. to 520° C. Also, the second processing gas obtained by reducing the temperature of the first processing gas through the heat exchange action has a temperature range of 230° C. to 280° C.

That is, in the heat exchange unitof the present inventive concept, a second exhaust gas having a higher temperature than the second processing gas is formed and transferred to the heating part. Also, in the present inventive concept, the symbols O and x are used to indicate the airflow. The symbol O means that the airflow flows out in a vertical direction from the ground, and the symbol x means that the airflow flows in in a vertical direction from the ground.

The heating parthas an exhaust gas supply part, a heater unit, and baffle plates.

The exhaust gas supply partis formed in a space between an inner housingand an outer housing. The space is filled with an insulating material. The exhaust gas supply part, which is provided in the form of a pipe between the insulating materials, minimizes heat loss due to the insulating material. The second exhaust gas is supplied through the exhaust gas supply part, and the second exhaust gas is introduced into the heating part.

The second exhaust gas is introduced into the heating partthrough the exhaust gas supply part. The heating partaccommodates the second exhaust gas whose temperature has been raised and performs a temperature-raising operation while inducing movement of the second exhaust gas to form a third exhaust gas. The third exhaust gas obtained by raising the temperature of the second exhaust gas has a temperature capable of reacting with the catalyst. The third exhaust gas whose temperature is raised through the heating parthas a temperature range of 750° C. to 900° C.

The heater unitof the heating partconverts electrical energy into thermal energy to perform an operation of heating the airflow, extends in a direction horizontal to the ground, is disposed spaced apart from each other, and heats the second exhaust gas to form a third exhaust gas. The heater unit may more quickly raise the temperature of the second exhaust gas as the contact frequency with the second exhaust gas increases.

The heater unitspass through the baffle plates, and the plurality of baffle platesare disposed in a direction perpendicular to the ground. Through the installation structure of the baffle plates, the flow of the second exhaust gas is guided to flow in a direction perpendicular to the ground.

The flow of the second exhaust gas flowing between the plurality of heater unitsis controlled by the baffle plates. The baffle platesare made of nickel-containing heat-resistant alloy steel having strong corrosion resistance. The second exhaust gas repeatedly moves in a vertical direction from the ground due to the baffle platesand is heated by the heater unitsto form a third exhaust gas.

The heating partand the catalyst unitare integrally formed and may be configured within a single housing that accommodates the heating partand the catalyst unit. That is, in the present inventive concept, the heating partand the catalyst unitare accommodated in a single housing without any separate inner piping. In particular, the housing has an outer housingand an inner housing. Also, the insulating materialis filled between the outer housingand the inner housing. The insulation effect of the catalyst unitinstalled in the inner housingis enhanced due to the two housingsandand the insulating materialinterposed therebetween. That is, the catalyst unitis installed within the inner housingto minimize a phenomenon of heat being released to the outside of the equipment.

The catalyst unitis directly connected to the heating partand is installed in the inner housing. The catalyst unithas a plurality of partitionsand a catalyst aggregate. The partitionsare installed in a direction perpendicular to the ground and are disposed a predetermined distance apart, and the catalyst aggregatecomposed of catalyst particles is disposed between the partitions.

A space is formed between the catalyst particles, the third exhaust gas flows through the space, perfluorinated compounds and nitrous oxide are decomposed through a catalytic reaction, and a first processing gas is formed. The first processing gas is in a relatively high temperature state and is introduced into the heat exchange unit.

In the heat exchange unit, the temperature of the first processing gas is reduced through the heat exchange action to form a second processing gas, and the second processing gas is allowed to flow a cooler. By reducing the temperature of the first processing gas, the temperature of the first exhaust gas is raised in two stages to form a second exhaust gas.

is a side cross-sectional view for explaining the operation of the heating part and the catalyst unit ofaccording to a preferred example embodiment of the present inventive concept.

Referring to, the heating partand the catalyst unitare installed in the inner housing, and the outside of the inner housingis filled with the insulating material.

The second exhaust gas is introduced through the exhaust gas supply part, and the second exhaust gas is introduced from the upper side of the inner housing. When the second exhaust gas is introduced from the upper side or top of the inner housing, the airflow direction of the second exhaust gas is guided in a direction perpendicular to the ground by the baffle plates. That is, an airflow flowing in a zigzag pattern in the vertical direction is heated through the heater unit.

In the heating part, the second exhaust gas flows between the baffle platesand is heated while moving from the top to the bottom or from the bottom to the top. Through this, the contact frequency of the airflow with the heater unitdue to the baffle platesincreases, and the temperature of the second exhaust gas is quickly raised to form a third exhaust gas.

The third exhaust gas is introduced into the catalyst unit. The catalyst unitis composed of the partitionsand the catalyst aggregate, and the catalyst unitis directly connected to the heating part. The partitionsconstituting the catalyst unithave a shape with a partially open upper or lower portion and have a structure that guides the airflow introduced into the lower portion toward the upper portion or guides the airflow introduced into the upper portion toward the lower portion. That is, the partitionshave an open shape arranged in a zigzag pattern in the vertical direction and allow the third exhaust gas to come into contact with the catalyst particles as much as possible.

Also, when the last baffle platethrough which the third exhaust gas of the heating partis discharged has a shape with an open upper portion, the partitionthat initially accommodates the third exhaust gas has a shape with an open lower portion. Also, when the bottom of the last baffle platethrough which the third exhaust gas is discharged has an open shape, the partitionthat initially accommodates the third exhaust gas has a shape with an open upper portion. That is, the third exhaust gas is preferably designed to flow through the heating partand the catalyst unitin a zigzag pattern in the vertical direction.

When the direction in which the last baffle plateof the heating partis open is the same as the direction in which the first partitionof the catalyst unitis open, the third exhaust gas may not flow in the vertical direction along the partitions, but may be introduced directly into the catalyst unit. However, a region in which the third exhaust gas is stagnant without any movement appears in a space between the last baffle plateand the first partition. In the stagnant region, the third exhaust gas may cause compounds or impurities to be deposited on the first partitionor the last baffle plate, thereby deteriorating the performance of the apparatus.

The partitionsare disposed perpendicular to the lower or upper surface of the inner housingto induce the airflow to move up and down in a zigzag pattern.

The catalyst aggregateis disposed between the partitions. In order to prevent the catalyst particlesof the catalyst aggregatefrom being detached through an open region between the partitionsand the inner housing, the catalyst aggregatemay be provided in a state in which the catalyst aggregateis accommodated within a mesh.

The catalyst aggregateis composed of a plurality of catalyst particles. The perfluorinated compounds and nitrous oxide are decomposed as the third exhaust gas flows through the space between the catalyst particles, and the first processing gas is formed. The following reaction occurs due to the contact between the catalyst particlesand the third exhaust gas.

That is, the perfluorinated compounds and nitrous oxide in the third exhaust gas may be removed by being respectively converted into hydrogen fluoride (HF), nitrogen (N) and the like while passing through the catalyst unit. In particular, the decomposition reaction due to the catalyst particlesmay occur smoothly due to the high-temperature third exhaust gas.

A processing gas outletconfigured to discharge the first processing gas is provided at the rear end of the catalyst unit. The first processing gas is supplied to the heat exchange unit through the processing gas outlet.

is a side cross-sectional view showing the catalyst unit according to a preferred example embodiment of the present inventive concept.

Referring to, the catalyst unit has partitionsand a catalyst aggregate. The partitionsare made of a highly corrosion-resistant material such as an SUS material, and have an open space adjacent to the upper or lower region of the inner housing. The third exhaust gas is introduced into the catalyst aggregatethrough the open space. Also, the catalyst aggregateis composed of catalyst particlesfilled between the partitionsspaced apart from each other.

Specifically, the catalyst particlesmay include zinc aluminate, a perovskite oxide, and a binder. That is, when the catalyst particlesare composed of a single catalyst in which a perovskite oxide containing lanthanum (La) and strontium (Sr) is mixed with zinc aluminate, the catalyst particlesmay simultaneously decompose the perfluorinated compounds and nitrous oxide without generating by-products such as carbon monoxide due to the stable catalytic activity maintained even in a redox atmosphere, and have excellent thermal and chemical stability at high temperatures, which makes it possible to maintain the perfluorinated compound and nitrous oxide removal performance for a long time.

The zinc aluminate (ZnAlO) may be used with an atomic ratio of aluminum (Al): zinc (Zn) of 2:1. The zinc aluminate may be manufactured by a conventional manufacturing method such as direct impregnation of γ-alumina using a zinc precursor, a precipitation method by pH regulation, or the like. Preferably, the zinc aluminate may be manufactured by first mixing boehmite, which is a γ-alumina precursor, and a zinc precursor to obtain a mixture and then heat-treating the mixture. The zinc aluminate manufactured by the method has a high endothelial toxicity effect, and may be used for a longer period of time than existing catalysts that are difficult to use for a long period of time and require frequent replacement.

The zinc precursor may be at least one selected from zinc sulfate hydrate [ZnSOHO], zinc acetate [(CHCO)Zn], zinc nitrate [Zn(NO)], all of which contain zinc. Also, boehmite is an aluminum oxide hydroxide represented by the following chemical formula: AlO(OH), and boehmite is commonly used as a γ-alumina precursor. When bayerite or Trierite is used in addition to the boehmite, the endothelial toxicity effect cannot be expected, and the endothelial toxicity effect may be maximized only when boehmite is used. When the boehmite is used, the boehmite precursor in the form of a suspension, a sol, or a slurry may be converted into boehmite granules formed as particles or crystals by subjecting the boehmite precursor to heat treatment such as hydrothermal treatment.

The perovskite oxide may be a perovskite oxide represented by the following Compositional Formula 1.

In this case, in Compositional Formula 1, x may range from 0.4 to 0.8, and may preferably be 0.6.

In Compositional Formula 1, when x is less than 0.4, the crystal structure changes to a cubic, tetragonal, or orthorhombic structure due to the excessive amount of strontium, thereby reducing the catalytic activity. On the other hand, when x is greater than 0.8, the perovskite structure may collapse due to the small amount of strontium, which results in significantly reduced catalytic activity and durability.

The perovskite oxide may ensure sufficient thermal stability under high-temperature conditions and chemical stability under various chemical environmental conditions. In fact, the catalyst particlesof the present inventive concept containing the perovskite oxide may efficiently control catalyst deactivation by significantly reducing a sintering phenomenon even at a high temperature near 800° C.

The perovskite oxide may be manufactured as an oxide having a perovskite structure by a conventional manufacturing method using a lanthanum precursor and a strontium precursor. At this time, the lanthanum precursor and the strontium precursor may be nitrates, alkoxides, chlorides, hydroxides, oxyhydroxides, carbonates, acetates, oxalates, and mixtures thereof, all of which include lanthanum and strontium.